Viral Assays Core ? SUMMARY Core B is a Viral Assay Core serving the three Projects. The overall goal of this U19 proposal is to define the cellular immune response to persistent viral infection within tissues of the host. The immune response controlling the persistence of a complex DNA virus, such as human cytomegalovirus (CMV), is poorly understood. CMV infects a multitude of different cell types in its host, resulting in a dynamic persistence marked by intermittent or persistent antigen presentation that shapes the immune response to infection in tissues where the virus persists. Preliminary data presented in this proposal defines the presence and unique functional profiles of CMV-specific T cells within tissues of infected individuals. It is critical to consider the presence of the virus in defining profiles and function of T cells, DCs, and macrophages responding to persistent infection. Aim 1 of the Viral Assay Core is to profile tissues and blood from human organ donors and blood from transplant patients the presence of viral genomes. We will also define the DC and macrophage cell types within tissues that harbor latent virus. Aim 2 of the Viral Assays Core is to provide infected cells and cell free virus for functional assays proposed in DCs and macrophages. The PI of this core has extensive expertise in CMV infection and latency in specialized primary human cell models necessary to carry out this aim. This service core will allow immune cell presence and function to be correlated to the presence of virus in specific tissues in the host. Considering the presence of virus in tissues is critical in defining the immune response to viral persistence.